| Date | Speaker | Affiliation | Title | Abstract |
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| Oct 1 |
Dmytro Volin |
TCD |
Classification of unitary representations of su(n,m|k) Lie superalgebras |
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Abstract:
It is well known how to classify all unitary representations of compact algebras su(n) and su(n|m), as well as all highest-weight unitary representations of non-compact su(n,m) case. However, quite surprisingly, the generic su(n,m|k) situation was not properly understood except for special choices of n,m,k.
In this talk I will cover this gap and give the full classification of the unitary representations. All of them appear to be of highest-weight type, but with some weights being continuous rather than discrete. Despite this continuity in the spectrum we are still able to realise all representations using oscillators and therefore to prove the classification theorem easily. The resulting answer can be depicted in terms of generalised Young diagram inside the so-called T-hook which originally was proposed in the context of AdS/CFT integrability.
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| Oct 15 |
Laine, Mikko |
U. of Bern |
Can heavy ion collision experiments teach us something about cosmology? |
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Abstract:
Both heavy ion collision experiments and cosmology offer examples of relativistic plasmas in which some particle species are out of equilibrium. The out-of-equilibrium particles play little role for bulk thermodynamic properties such as the overall pressure of the system, but are of vital importance as observable 'relics' from the thermal epoch. In this talk some basic concepts of out-of-equilibrium thermodynamics are reviewed, and the question posed in the title is pondered with the example of dark matter in cosmology versus heavy quarks in hot QCD.
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| Oct 22 |
Stefanski, Bogdan |
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Holographic integrability for AdS3/CFT2 |
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Abstract:
The AdS3/CFT2 correspondence is one of the earliest known examples of holographic duality. It is an example of holography which involves the renormalisation group flow of a non-conformal gauge theory; it features prominently in the discussion of black-hole entropy computations as well as offering a definition of quantum invariants in a variety of geometrical settings.
I will review recent progress in using integrable methods to understand the planar limit of the AdS3/CFT2 correspondence. I will present the complete non-perturbative S-matrix for the worldsheet excitations of the string theory. In particular I will show how to incorporate massless modes into this description - something that, until now, has been a major stumbling block in the integrability approach.
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| Oct 29 |
Anosh Joseph |
DESY Zeuthen |
Supersymmetry on a Spacetime Lattice: Recent Developments |
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Abstract:
Several classes of supersymmetric theories can be discretized on a Euclidean lattice by preserving at least one supersymmetry exact at finite lattice spacing. I will detail the lattice formulations of supersymmetric gauge theories with four, eight and sixteen supercharges, with and without matter. Having a first-principles definition of supersymmetric gauge theories, through lattice discretization, would provide a window into their non-perturbative sectors. I will also briefly describe the Monte Carlo techniques used to study these theories at strong coupling.
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| Nov 12 |
Waldemar Schulgin |
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Asymptotic symmetry group of the flat space string theory |
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Abstract:
I will explain how to obtain the asymptotic symmetry group
of the target space from the worldsheet perspective. I will review the
AdS3 case and explain what are the difficulties to take the zero limit
of the cosmological constant. I will realize the asymptotic symmetry
group of three-dimensional flat space (BMS3-group) in terms of vertex
operators on the string worldsheet. Motivated by the BMS3 construction I will discuss vertex operators associated with space-time diffeomorphisms in flat space string theory, and compute their algebra, which is a diffeomorphism algebra with higher derivative
corrections.
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| Nov 19 |
Mukund Rangamani |
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Quantum entanglement and holography |
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Abstract:
I will review the holographic methods to compute entanglement entropy. In particular, I will focus on general properties that the holographic construction must satisfy such as causality, respecting entropy inequalities etc..Time permitting I will describe other measures of quantum information and the clues they might hold for holography.
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| Nov 26 |
Epelbaum, Evgeny |
Bochum |
Cancelled |
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| Dec 3 |
Della Morte, Michele |
Odensee |
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Abstract:
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| Jan 14 |
Cristophe Royon |
Saclay |
Forward Physics with tagged Protons at the LHC |
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Abstract:
After defining diffraction in particle physics, we will describe briefly some of the physics topics that can be studied at the LHC using tagged protons, namely QCD and the structure of the pomeron in terms of quarks and gluons, as well as the search for extra-dimensions in the universe via anomalous couplings between photon, W and Z. We will finish the seminar by describing briefly the new detectors that will be installed to achieve these measurements.
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| Jan 21 |
Evgeny Epelbaum |
Bochum |
What Holds the World Together? Modern Theory of Nuclear Forces |
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Abstract:
Chiral effective field theory provides a powerful theoretical tool to describe nuclear forces and low-energy reactions in few-nucleon systems. Recently, a discretized version of this approach has been developed, which allows one to access heavier systems by using Monte Carlo simulations to describe propagation in Euclidean time. I will outline the foundations of both the continuum and discretized formulations and discuss selected applications focusing, in particular, on the light quark mass dependence of nuclear observables.
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| Jan 28 |
Pelaez, Jose |
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| Feb 4 |
Gabor Takacs |
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Special Time:
Fri Feb 6 2pm |
Erik Verlinde |
Amsterdam |
Symmetric Product CFT's and The Hawking Page Transition |
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Abstract:
For symmetric product CFT's the free energy can be calculated in a grand canonical ensemble in which one introduces a chemical potential for the central charge of the CFT. The result turns out to be symmetric in the chemical potential and the inverse temperature. It is well known that CFT's with a gravity duals exhibit a Hawking Page transition at fixed central charge when the temperature exceeds a critical value.
For symmetric product CFT's there is a similar transition at fixed energy when the chemical potential falls below a critical value. In this talk I will discuss the physical interpretation of this transition, and comment on its possible generalization to other type of CFT's.
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Special Time:
Fri Feb 6 3:30pm |
Nikita Nekrasov |
SCGP & IHES |
Non-perturbative Dyson-Schwinger equations in N=2 susy gauge theories |
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Abstract:
We study non-local symmetries of quantum field theory which relate topologically distinct sectors of the field space. In the context of the BPS/CFT correspondence, using the qq-characters observables, we derive an infinite set of Dyson-Schwinger-type relations, including the Knizhnik-Zamolodchikov(-Bernard) equations, and Belavin-Polyakov-Zamolodchikov equations, obeyed by the supersymmetric partition functions of N=2 gauge theory in the presence of Omega-deformation and defects. The qq-characters generalize the q-characters of quantum affine algebras and Yangians.
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| Feb 11 |
Romuald Janik |
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| Feb 18 |
Zohar Komargodski |
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| Mar 4 |
Jan Plefka |
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| Mar 25 |
Sergei Alexandrov |
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| Apr 1 |
Gleb Arutyunov |
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